Electrostatic generator with charging and collecting arrays

ABSTRACT

A device is described for transducing heat-kinetic power into electrical power using a charged aerosol, which flows through a sheet conversion space having emitting and exciter arrays to charge and form droplets at the entrance plane and a collector array to discharge the droplets at the exit plane and to supply electrical power to load; which results in increased efficiency with greater output power and current at a smaller voltage.

FIFBEEGE Mme mates Patent 1 1 Marks 1 1 Feb. 12, 1974 l 54]ELECTROSTATIC GENERATOR WITH 3,206,625 9/1965 SluclZer 310 (1 CHARGINGAND COLLECTING ARRAYS 2,885,599 5/1959 Hand 310/5 X 2,277,712 3/1942 m310/5 11x Inventor: Alvin Marks, 149-61 l 2,308,884 1/1943Lindenblad.... 310/5 Cove Blvd, Whitestone, N.Y. 2,208,217 7/1940Landerhulm 310/5 1 1357 3,225,225 12/1965 Wattcndorf ct a1 310/6 [22]Filed: Nov. 22, 1971 163] Continuation-impart of Sen No. 16,048, March3,

1970, abandoned.

[52] LS. Cl. 310/5, 310/11 [51] Int. Cl H02 [58] Field of Search 310/2,4, 5, 6, 11,7,

[56] References Cited UNITED STATES PATENTS 3,411,025 11/1968 Marks310/5 X Appl. No.: 200,766

Related US. Application Data Primary ExuminerD. F. Duggan 1571 IABSTRACT A device is described for transducing heat-kinetic power intoelectrical power using a charged aerosol, which flows through a sheetconversion space having emitting and exciter arrays to charge and formdroplets at the entrance plane and a collector array to discharge thedroplets at the exit plane and to supply electrical power to load; whichresults in increased efficiency with greater output power and current ata smaller voltage.

8 Claims, 16 Drawing Figures ELECTROSTATIC GENERATOR WITH CHARGING ANDCOLLECTING ARRAYS This application is a continuation in part of anapplication filed Mar. 3, 1970, Ser. No. 16,048, now abandoned entitled:MULTIPLE POINT DYNAMIC GEN- ERATOR, invented by ALVIN M. MARKS.

BACKGROUND OF THE INVENTION Several heat-electrical power conversiondevices have been described employing a high velocity charged aerosolgas as a transducer in U.S. Pat. Nos. 3,417,267, 3,411,025 and 3,191,077issued to Alvin M. Marks. U.S. Pat. No. 3,417,267 describes a deviceusing an Expansion-Condensation Process to produce a charged aerosol bygas-vapor expansion and cooling and condensing the vapor to form chargeddroplets on ions emitted from a point in an electric field. U.S. Pat.No. 3,411,025 describes a device using a Mixture- Condensation Processwhich produces a charged aerosol from a superheated vapor mixed with acooler carrier gas to form charged droplets by condensation of the vaporonto ions emitted from a point in an electric field.

In U.S. Pat. No. 3,191,077 a method known as the Electrojet Process isdescribed for forming a charged aerosol in which the emitter is a smalldiameter tube containing a liquid carried by a moving gas in an electricfield to form charged droplets. In a copending patent application, Ser.No. 648,403 filed June 23, 1967, various processes are describedembodying these and other principles which are employed to charge andform submicron droplets of optimum mobility for efficient powertransduction.

In U.S. Pat. No. 3,225,225, issued to Wattendorf, et a1, there is shownwell scattered points along a series of slit nozzles. There is one pointin the center of each slit nozzle. The distance between the pointsexceeds the width of the slit.

In prior art devices a narrow passage or long thin channel in the formof a nozzle or tube was employed for the conversion space. The proximityof the electrodes to the wall often caused electrical discharges to andalong the wall surface shorting a portion of the converted power,resulting in a loss of efficiency.

In the present invention the term per unit area" means per mm*.

For many purposes a large power output is required at small voltage andlarge current. Because of the space charge effect, at incipient sparkbreakdown, the generated voltage and the current are in direct andinverse proportions to the conversion lengths, respectively. In thepresent invention this requirement is met by employing as a chargedaerosol conversion space a large area in the shape of a thin disc or asheet, having a diameter to thickness ratio of at least three to one andpreferably or more; and in which the thickness is 2mm or less. A uniformcurrent density across the charged aerosol space sheet is provided by anemitter array comprising a large numerical density of emitter sources.per unit area of the space sheet and a collector array have largenumerical density of discharge elements per unit area.

It is often required to combine these requirements with a nozzle forconversion of the heat kinetic power. To accomplish this, a nozzle arraymay be provided containing in each nozzle, emitter and collector arrayswith suitable exciter electrodes. The large area thin conversion spaceenables power conversion to occur within a space sheet of chargedaerosol spaced from the wall, to avoid the wall shorting effect.

A feature of this invention is the use of arrays comprising a highnumber density per unit area of emitter and collector elements, whichpermits of a decrease in the conversion space length. This arrangementresults in a more uniform charged aerosol having a higher currentdensity and smaller exciter and output voltages. These factors result ina generator which is more compact and more efficient.

A feature of one embodiment of the present invention is the simultaneousformation of charged aerosol droplets over a large area by mixing avapor and a cooler gas in the vicinity of a large area ion emitter arrayof high point density per unit area.

A feature of another embodiment of this invention is the employment ofan emitter array comprising electrojet sources of charged droplets.

A distinguishing feature of this specification is the high numberdensity of emitter per mm which results in a small current emitter peremitter; but the total current per square millimeter is the current perpoint times the number of point per mm This results in a greatlydecreased voltage between the emitter and the exciter electrodes. Ashorter conversion space can be employed.

A further feature of the invention is the provision of emitter arrays inwhich the minimum point density is related to the conversion length.

A further feature is an optimum geometry for an ion emitter array ofhigh point density, an exciter, and an orifice plane, to provide maximumcurrent at minimum exciter-emitter voltage.

Still another feature of the invention is an emitter array containing aplurality of emitters actuated by a single exciter electrode.

For a better understanding of the present invention, together with otherdetails and features thereof, reference is made to the followingdescription taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. I is a schematic diagram ofconnections showing the entire system according to the present inventiontogether with the pumps, condenser, and boiler necessary to operate thegenerator.

FIG. 2 is a cross sectional view of one form of the invention, showingthe electrodes and the manner in which the gas and vapor are mixed.

FIG. 3 is a sectional view of a generator nozzle and its gas and vaporinlets showing one of the linear array of point emitters, with spacingsymbols used in the mathematical analysis given hereinafter.

FIG. 4 is a cross sectional view taken on line 4-4 in FIG. 3, showingthe linear array of point emitters.

FIG. 5 is a cross sectional view of another generator in accordance withthe present invention showing an emitter array and associated structure.This view is taken along line 5-5 of FIG. 6.

FIG. 6 is a cross sectional view of the generator shown in FIG. 5 and istaken along line 6-6 of that view.

FIG. 7 shows a high density ionizer point array interspersed with vaporjet orifices, another embodiment of the present invention.

FIG. 7A is a cross sectional view taken on line 7a-7a in FIG. 7.

FIGS. 8A and 8B show emitter and collector arrays in an idealizedconverter, 8A being the front view of the array and 8B the side view ofthe array, with spacing symbols used in the mathematical analysis.

FIG. 9 shows an orifice point exciter geometry utilized in a testgenerator.

All graphs shown in FIGS. 10 to 14 inclusive are plots of experimentaldata for a linear array of point-emitters in air for no gas flow at STP,taken on the device shown in FIG. 2 having the geometry shown in FIG. 9.

FIG. 10 shows the relationship between the voltage and current for asingle point emitter for the orifice plane-exciter distance a 4.5lmm,and where the emitter-exciter distance x varied.

FIG. 11 shows maximum current and voltage versus the distance a betweenthe exciter and orifice plane, for a fixed point emitter-exciterdistance x 1.75mm.

FIG. 12 shows the total current and potential difference between emitterand exciter for I, 3, 17, and I9 points, for a 9.4mm, x 4.5mm and L2.3mm.

FIG. 13 shows a maximum current and breakdown voltage vs. number ofpoints N, for a spacing of L 2.3mm; the maximum current per point i vs.the number of points; and the peak breakdown voltage vs. the number ofpoints N.

FIG. 14 shows a log-log plot of the electric field intensity E vs. i,,the current per point for I to I9 points with 9.4mm, x 4.5mm and L2.3mm.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, acomplete generator closed loop system is shown diagrammatically in whichthe generator 10 includes an emitter array Ill, an exciter array 12, anda collector array 13. The emitter side of the generator 10 receives acondensable vapor such as steam through a conduit 14 from a boiler 15and a superheater 16, and a gas such as hydrogen or air through a secondconduit 16 from a gas heater 17. The boiler 15 receives a vaporizableliquid such as water from a pump 18 and the gas heater 17 receives thegas from a gas pump 20. Power to supply the pumps 18 and 20 may beinitially from an external source, but after startup may be bled offfrom this generator. Heat at a suitable temperature to vaporize theliquid in boiler 15, superheat the vapor at 16, and heat the gas inheater 17 is supplied by a heat source, not shown, which may be gas, oilor nuclear.

An optimum charged aerosol droplet of a small mobility necessary forpower generation is formed by Mixture-Condensation of the vapor with asomewhat cooler saturated carrier gas to produce a droplet of about 200A diameter around an ion from the emitter.

If ions or droplets were to have a much smaller diameter, they wouldhave too large a mobility, which would cause too large a proportion ofthem to travel to the exciter electrode, rather than downstream to thecollector electrode, with a consequent loss of power and efficiency.

The emitter point electrodes from an array 11 connected to a commonterminal 21, which may be grounded. The collector point electrodes forman array connected to a first terminal of an electrical load 22. Asecond terminal of the load is connected to the emitter terminal 21. Theexciter electrodes form an array 12 which are connected to a highpotential low current source 23. Ions are emitted from points on theemitter array into the gas vapor. The potential source 23 may be, forexample, a battery or another generator. As shown in FIG. 1, a singleexciter electrode may serve to excite many emitter points.

After being discharged by the collector array, the aerosol is directedthrough conduit 24 to a condenser and separator 25. Here the aerosolliquid droplets are consolidated to a liquid body and return via pipe 26and water pump 18 to boiler 15. The gas which may be hydrogen or airpasses through conduit 27 to the gas pump 20, closing the loop back tothe generator.

Referring now to FIG. 2, one form of generator is shown in crosssection. In this device the emitter points 11 are grounded to thegenerator body. The base 28 supports an insulator 40 containing an axiallead-inconductor 38 to the exciter electrode 12. Point emitter rod 11 issealed in hole 31 by a gasket 32 to seal the high pressure vapor. Thebase 28 has a first conduit 33 for conveying the vapor from pipe 14 toan annular space 34 and the space surrounding the emitter points Ill,and a second conduit 35 coupled to conduit 39 for conveying heated andcompressed gas to the space 36. The emitter points 11 are connected tothe grounded base. The exciter electrode 12, is connected to a voltagesource (not shown). A stand-off insulator 37 is attached to the base 28.

A cylindrical block 41 is fitted onto the base 28 and supports two discs42 and 43. Disc 42 supports an insulated slit nozzle 44 in which theconversion space 54 is located. Discs 45 and 46 retain the slit nozzle44. The walls of the slit nozzle 44 are formed of insulating materialsuch as aluminum oxide. The emitter points 11 and the collector points13 comprise arrays. The collector potential is led off through a tubularinsulator 47 and a block insulator 48. The block 48 is secured to disc43 by disc 50. Gaskets 55, 56 and 57 seal the high pressure gases withinthe chamber 51. The space 51 between discs 42 and 43 acts as a reservoirfor the deionized vapor gas mixture. Pipe 24 connects space 51 to thecondenser and separator 25.

Gas and vapor are simultaneously introduced through pipes 39 and 14,respectively. The temperature of the carrier gas in the space 36 ismaintained below the temperature of the vapor jets issuing from theorifices 58. The emitter array points 11 are axially located within thevapor jets issuing from orifices 58 as shown in FIG. 3. When an electricfield is applied from the exciter electrode to the electrode points,ions are emitted into the vapor jet and cooler gas mixture. Gas vaporand ions are mixed and flow toward the slit nozzle droplets and aportion of the vapor condenses to form charged aerosol droplets ofsubmicron size. Within the nozzle, the charged aerosol droplets in thecarrier gas build up a space charge, and convert the heat-kinetic powerof the gas stream to electric power suppled to collector array 13. Thecharged aerosol droplets are neutralized by ions of opposite sign fromthe points of the collector array 13, which is at a potential somewhatbelow the peak space charge potential at the exit plane of theconversion space 54. A connection to the electrode 13 is brought outabove insulator block 48 where it is connected to a lug 53 and the load22.

The generator shown in FIG. 2 uses a plurality of emitters mounted in alinear array, and a similar number of collector electrodes in anotherlinear array. A

linear or one dimensional array is shown in FIGS. l-6, inclusive.Alternatively, the two dimensional array shown in FIGS. 7, 8A and 8B maybe used.

Referring now to FIGS. 3 and 4, a generator with a slit nozzle 59 isshown in diagrammatic form with a linear array of I9 emitters connectedtogether. The collector array 13 is identical to the emitter array II. Asingle exciter electrode I2 comprises two parallel straight conductorsHA and 128 connected together to form a rectangular metal stripconnected to conductor 33, and thence to a potential source 23 shown inFIG. I.

FIGS. 5 and 6 show another generator arrangement. The plan view of theemitters indicates their spaced relation. As before a collectorelectrode 13 is positioned in axial alignment with each emitter 11. Asingle exciter plate 49 with aligned circular holes is used.

In FIGS. 7 and 8 there is shown a point emitter array 60 in which jetsof vapor 61 such as steam, are emitted from orifices 62 formed at theinterstices between the closely packed point emitters 63. In this figurea cooler carrier gas 64 is mixed with the vapor jets 61, which containions 65 emitted from the points 63. The cooler carrier gas 64 causes thesteam jets 61 to condense about the ions to form charged aerosoldroplets 66. In this point array every point is equi-distant from theexciter electrode 67, at a distance R a x, where x is a minimum distancebetween the point on the array and the ground plane 68, and a is thedistance between the ground plane 68 and the exciter electrode. Eachpoint is subject to the same electric field intensity, and thereforeemits the same current, providing a uniform current density across theentrance of the converter space.

Alternatively, vapor may issue from a porous medium 62a in which thepoints 63 are embedded.

An another alternative, in an electrojet emitter array having a largenumber of electrojet emitters per unit area, relatively low voltagesapplied during the formation of the charged aerosol droplets from theelectrojet emitters, may enable the uniform formation of an optimumcharged aerosol.

FIG. 8A shows the idealized geometry of a two dimensional array employedin providing a charged aerosol sheet of large cross section and smallthickness L, corresponding to a conversion length L. The FIG. 8A

shows a unit area of the sheet, comprising an emitter or collector arrayhaving a spacing between points L The FIG. 8B shows a section throughthis sheet showing the separate emitter and collector arrays; and anarrow U shows the direction of the velocity of the moving chargedaerosol which constitutes the current thru the sheet conversion space.

FIG. 9 shows the geometry of a linear emitter array of 19 points andorifices used for tests on a power converter of this invention. Spacingsymbols are indicated together with the dimensions used in theexperimental tests shown in FIGS. 10 through 14 inclusive. For theemission of a maximum current from this array at incipient sparkbreakdown in air at STP, optimum ratios found from these tests were (x/L1.68, (a/x) 2.43; and (a-x)/L 2.41. The maximum current from the 19points was about I milliamp with no gas flow, and about 1.5 milliampswhen air flows through the 19 orifices surrounding the points.

It is preferred to employ a greater point density so that the currentemitted from each point is substantially less that this maximum current,which results in a decrease in the potential difference between theexciter and the emitter points.

The discovery on which the present invention is based is shown in FIG.14, in which the electric field intensity between the emitter andexciter electrodes decreases as the current per point decreases,however, the total current may be kept constant by increasing the numberof points per unit area. Equation (I3) shows the relationship betweenthe cmitter-exciter electric field intensity and the point density. Thisis fur ther discussed below on Page 16, lines 9 through 12.

A decrease in current per point from T0 ua to l 1.21 per point resultsin a decrease of the emitter-exciter electric field intensity from 480to 420 volts per millimeter. A single controlling spaced point at micronamperes per point required an emitter-exciter electric field of 900volts per millimeter. Utilizing a still greater number of points thevoltage may be still further decreased.

A further advantage of an increased emitter point density is that a moreuniform current density can be obtained, and the conversion length maybe decreased. This decrease in conversion length has the advantage ofenabling higher currents and lower voltages to be obtained during thepower conversion.

In practice, the decreased field intensity is obtained by utilizing atleast one point per mm Projecting a linear increase in current withpressure, at 40 atmospheres a maximum current of 60 milliamps may beexpected from the 19 points per cm At an output power density of 1 KW/cmat IOOKV and 40 atmospheres then the maximum current density is:

i= 10 /10 l0 amps/cm or l0ma/cm Consequently, the present ionizer isadequate to supply the current required for l-IO KW/cm power density.

In the tests shown in FIGS. 10-14 inclusive important new relationshipswere discovered between the point density and the electric variables inan eleetrogasdynamic generator. The maximum current per point atincipient breakdown decreased exponentially with the number of points to5 points; and reached an asymptotic constant value as the number ofpoints increased. For more than 5 points, the maximum current isapproximately proportional to the number of points. For maximum currentemission there is an optimum distance of the emitter points between theground plane and the exciter electrode. The exciter voltage decreaseswith point density. There is a minimum point density n for a givenconversion length L needed to provide the charged aerosol current atmaximum power density. The minimum point density is proportional to gasvelocity and inversely proportional to the converter length; and isindependent of gas density and power density. A greater point densitythan the theoretical minimum is required to provide a uniform chargedaerosol distribution for conversion lengths under 5mm; and to decreaseexciter voltage.

The generator shown in FIG. 2 employs the Mixture- Condensation Processin which charged aerosol droplets are produced by the Condensation ofsteam jets onto ions induced by mixing the steam jets with a coolercarrier gas. In the Expansion-Condensation Process an almost saturatedvapor at the inlet to the nozzle is subsequently cooled by expansiononly in the presence of ions to form charged aerosol droplets.

Comparing experimental results obtained with the generator of FIG. 2,which employed the Mixture- Condensation Process with the resultsobtained with the Expansion-Condensation Process, the power densityincreased 2.8 times at the same gas density. The charged aerosolbreakdown factor for the Mixture- Condensation Process was k 1.12 forwater vapornitrogen compared to a charged aerosol breakdown factor forthe Expansion-Condensation Process of k, 0.67 for water vapor-air;(,/k,) 2.8.

In FIG. 8B the charged aerosol particles 66 are shown in a conversionspace 70, which comprises a large area sheet of thickness L. In a verythin sheet the charged aerosol gas may flow through with little or nochange in velocity, and electric power output results from a decrease inheat power, temperature and pressure across the sheet conversion space.However, in sheets where d/L 25, a small increase in the diameter of thesheet from the entrance to the exit plane enables a considerableelectric power output to be obtained from a corresponding decrease inkinetic power.

MATHEMATICAL PHYSICS ANALYSIS SYMBOLS See FIGS. 3, 4, 7, 8A, 8B and 9showing symbols relating to the emitter and collector geometry.

a distance of orifice plane to exciter electrode a, (b, e,,/2) (bk) 42(b,,k power constant a, (c m/I) (b k) array constant a =(b,, e,,/8,,)72, friction constant b, relative electric breakdown factor of thecarrier gas; or, the ratio of the electric breakdown intensity of thecarrier gas to that of air, at standard conditions.

b, 3.08 X 10 volts/m., which is the approximate electric breakdownintensity of free air at standard conditions.

C Sonic velocity at STP.

d diameter of conversion space or charged aerosol lsheet E electricfield intensity E,,, E, particular values of E I total current from Nemitters 1' current density i, a particular value of the current perpoint i,, a particular value of the current per point k breakdownstrength of the charged aerosol relative to the gas L length ofconversion space and thickness of charged aerosol sheet L, lengthbetween emitter points of array m, relative molecular weight, comparedto air N number of emitter points n number of emitter points per unitarea, or point density n,, reference point density, 2O/cm p,=electricpower density watts/m q exponential constant T,, absolute temperature(300 K) l U the carrier gas velocity in m/s V voltage x distance ofemitter points from orifice ground plane GREEK SYMBOLS 10 minimum valueex exciter in input out output EQUATIONS MAXIMUM CURRENT VERSUS NUMBEROF POINTS FIGS. -14 inclusive summarize the experimental results withstatic tests of the multipoint ionizer (1-20 points) with no gas orvapor flow at STP.

Curves were fitted to the observations, using the following empiricalequations: The maximum current per point versus the number of points N:

(I) The total peak current I versus the number of points N:

l= N[80e +50] uA (2) The optimum configuration had these parameters:

a 9.4mm; L, 2.3mm; 3.5 x 4.5

The equation (2) becomes approximately linear with N on the conditionthat N 5. Hence for 5 N and It is known that in a charged aerosolgenerator the maximum current? versus the relative density 8,, is:

To obtain a result in terms of n, the number of points per unit area forthe given current density, divide (6) through by the flow area A:

CURRENT PER POINT VERSUS ELECTRIC FIELD INTENSITY The curve of FIG. 14which shows the exciter-emitter electric field intensity E versus thecurrent per point i, falls into two distinct regions AB and CDapproximately by straight lines having the empirical equation:

In the range BC the curvature changes and the equation (8) cannot beused.

For the range AB: l6 ,aA/point, the constants in Equation (8) are:

Thus:

For the range CD: 25-50 ,ttA/point, the constants in Equation (8)change:

The decrease in the exponent q may be due to increased space charge atgreater current densities. This space charge is also decreased underdynamic conditions.

FIG. 14 may be extrapolated to a smaller current per point and a greaterpoint density, by extending the straight line AB:

E F g. (E/i.)

The current per point in terms of the point density n is From (I l) and(12) the relation between the point density n and the emitter-exciterelectric field intensity is:

E a n 1) 1 g) o) Equation (13) shows that with an increased pointdensity there is a decreased voltage between the emitter points and theexciter electrode. Thus, as i, is decrased from to 1 put per point, theelectric field intensity decreases from 480 to 420 volts/mm, a decreaseof 60 volts per decade. In a generator test there were 20 pointslcm or n0.2 point/mm for which i 50 rm and E 500 volts/mm.

Evaluating (13) from this data:

E 500 60 log (n/O.2)

It is now known that the output electric power density of the chargedaerosol generator is:

p e (b,, 6 /2) b k 5 U a,5,, U

(l5) where (b,, e /2) 42 (mks unit system) where a 42 (b,,k) The factora may be computed from (15) using these readily measured factors:

It is also now known that the output electric power density is alsoexpressed:

11 G i L /2 e U Combining equations (7), (l5) and (18), there is obtained 1 a (U/L) The result l 8) enables the calculation of the minimumpoint density 2 for a charged aerosol generator operating at maximumoutput power density. The result shows the 2 is independent of therelative gas density 8 Evaluating the array constant a using i 50,uA/point and b,,k 1.11 (c h /K) (b,,k) 8.85 X 10* X3Xl0 /5QXlO Xl.XlO.5 19) The spacing L between the points on a square array of a minimumpoint density 2 is:

To uniformly produce and distribute the charged aerosol in theconversion space it is required that L, 2L, that is B 2 0.5 for thecharged aerosol to be uniformly produced and distributed in converterswhere B 0.5 the point density n must exceed theminimum point density Todecrease the voltage between the emitter points and the exciterelectrode the point density n must 4 greatly exceed the minimum pointdensity, to decrease the current per point below the maximum current.Operating the emitter points below their maximum current outputdecreases the possibility of spark breakdown; there is less wear on thepoints, and the operation is more reliable.

In the generator shown in FIG. 2 the conversion length L 7.9mm and L2.3mm for 20 points; and L 16.7 for 2 points. To compute B for thisconfiguration for 20 points B 7.9/2.3 3.4; and for 2 points B 7.9/16.70.47

The latter B is too small and will not provide uniform distribution ofcharged aerosol in the conversion space.

A decreased converter length L lmm, is advantageous since for the sameoutput power density, p 5

l. The generator output voltage V is decreased.

2. The exciter voltage is decreased.

3. The generator output current I is increased.

For small converter lengths L 5mm the point den sity 11 must exceed theminimum point density to provide a uniform distribution of the chargedaerosol in the converter space.

V: 2.37 X 10 5 /U)"2L (24) or alternatively:

v 1.54 10" (h,,l 5,, L

Examples:

1. Given: E 460 volts/mm Find: i

Answer: i 1 (460/420) [3 6.0 ptA/point 2. Given: E 660 volts/mm Find: i

Answer: i 10 [l (1.5) 44 uA/point 3. Given: A point emitter array inwhich L 0.072 mm (approx. 3 mil) n 196 points/mm Find: Theemitter-exciter field intensity Answer: E 500 60 log (196/02) 320volts/mm 4. Given: p g 1 KW/cm 1.10 watts/m 4.2-L 0.25mm 0.25 X 10' m4.3The emitter-exciter distance is 0.2mm in (4.1)

4.4-The velocity is 360mm/sec and (b k) 1 Find: Output voltage V (a) in4.1 and (b) in 4.2 current density in 4.2; and (c) the minimum pointdensity n, L, and B and (d) exciter voltage for 4.3 Answer: From (27) VE 40,000 volts (b) For L 0.25mm (10 mils) V 10,000 volts 1' 1,000 amps/mor 0.1 amp/cm ()2= 0.5 (360/10) 1.8 X 10 points/m n 0.18 points/mm B=LILl/2.3 0.45

The test with an ionizer array performed without gas flow in air at 1atmos and 300 K gave the following experimental results:

A peak current was obtained with x 4 to 4.5mm. A value L 2.3mm, and 29.4 was chosen so that V would not be too great. The distance x betweenthe orifice ground plane and the emitters was varied. The number ofpoints N was varied.

A single point gave the largest current before breakdown. Increasing thenumber of points causes a decrease in the maximum current per pointbefore breakdown; but as the number of points increases, the maximumcurrent per point reaches an asymtotic constant value.

With more than 5 points the maximum current is nearly proportional tothe number of points N, or about 55 uA/point.

For 19 points, a maximum current of 980 ;/.A or about 1 milliamp wasobtained at a voltage V 4.2KV.

When air at 50 psi was applied to the orifices, moist airjets issuedfrom the orifices and the total current increased to 1.5 milliamps.

The breakdown voltage V decreased slightly as N increases, because of anincreased probability that spark breakdown will occur; and also possiblydue to small variations in distance x.

The current 1 increases with the distance to the exciter, but thepotential difference V also increases proportionally.

The V-l characteristics showed a great increase in current 1 above acritical value of V.

The maximum current per point i decreases exponentially to a constantvalue as N increases.

The maximum total current I increases approximately linearly with thenumber of points, N.

The emitter-exciter potential difference decreased to a minimum of about525 volts/mm for N 19 points at maximum current.

The minimum point density 2 in an emitter array is proportional to thegas velocity U, and inversely proportional to the length of theconversion space L, and is independent of the output electric powerdensity ea tbslaat A lq-.. a-

. 7 The exciter voltage and current decreases and hence the inputelectric power loss is decreased as n increases.

The voltage drop between the collector array and the peak potential of acharged aerosol decreases as the collector point density increases.

Above 30 atmospheres it is known that the current from a single pointdepartsfrom linearity and reaches a maximum. The use of multiple pointsassures that as much relationship as required can be drawn to maintaintbs s r d nsarrslatiqnshis between vq a e current and gas density formaximum electric power output, at all pressures, including pressures inexcess of 30 atmospheres.

The charged aerosol electric breakdown factor k for theMixture-Condensation Process with supercooled steam jets entering acooler-gas was k 1.12; compared to the Expansion-Condensation Processfor water and ethanol vapor in air for which the charged aerosolelectric breakdown factors are k 0.67 and 0.87 respectively.

The output power density produced by the Mixture- Condensation Processis greater than the output power density produced by theExpansion-Condensation Process by a factor of 2.75 times.

In the Mixture-Condensation Process the condensation is independent ofthe strong expansion as required in the Expansion-Condensation process.The kinetic/electric power conversion efficiency with steam and anitrogen carrier extrapolated to 8,, 53 (53 atm) is 3.2 percent perstage with air. For steam and hydrogen (H as the carrier gas; mr= l/14;b,,=0.67; and the extrapolated efficiency ism, '2 20 percent/stage.

An emitter array of 20 points/cm provides a more than adequate currentdensity by a factor of 10. This ionizer array should serve for thehigher pressures and output power density at atmospheres or more.

The minimum point density n is independent of the gas density and themaximum output power density.

For the same output current density, a larger emitter point density nresults in smaller current per point i A decreased current per pointresults in a decreased exciter-emitter electric field intensity.

A larger collector array point density results in a decreased voltagedrop between the charged aerosol and the collector.

The arrays described herein have emphasized ion emitting point arrays.However, the principles involving point density per unit area vs.converter length are also applicable to electrojet emitters of the typedescribed in US. Pat. No. 3,191,077. This specification is not limitedto point emitters, but includes electrojet emitters.

An electrogasdynamic power generation method has been described whichemploys a charged aerosol moving through a sheet conversion space, anemitter and exciter array to form and charge the aerosol droplets at theentrance plane, and a collector array to discharge the charged aerosoldroplets at the exit plane; and for which various methods of chargingand forming an optimum aerosol, previously described are employed.

Having thus fully described the invention, what is claimed as new anddesired to be secured by Letters Patent of the United States, is:

1. ln a power conversion device utilizing a charged aerosol as atransducer, an emitter array comprising a plurality of charge emittersto form and charge the charged aerosol, a conversion space to convertthe heat kinetic power of the charged aerosol to electric power, anexciter electrode for the emitters, said emitters per unit areaexceeding the number of exciter electrodes per unit area by a minimumpoint density of at least five points per exciter electrode, and acollector array for discharging the charged aerosol and transmitting theelectric power to an external load.

2. A device according to claim 1 in which the emitter array per exciterelectrode exceeds the minimum point density by one or more orders ofmagnitude and in which the distance between the exciter electrode andthe emitters is less than 2mm whereby the potential difference betweenemitter and exciter electrodes is less than 1,000 volts, wherein theminimum point density is n=a (U/L) where a is the array constant and isof the order of 0.5, U is the velocity of the charged aerosol in metersper second, and L is the length of the conversion space in meters.(whereby ions are emitted to form a charged aerosol in the conversionspace at maximum current density at incipient spark breakdown.)

3. A device according to claim 2 in which the conversion space length isless than 2 millimeters and in which the arrays exceed 1 point per mmemploying less than I00 volts potential difference between emitter andthe exciter electrode, providing output electric power at less thanl0,000 volts.

4. A device according to claim I in which a mixture condensation processis employed to charge and form the charged aerosol.

5. A device according to claim 4 in which superheated vapor is emittedfrom orifices between the point emitters.

6. A device according to claim 1 in which the emitter exciter andcollector arrays comprise linear arrays.

7. A device according to claim 1 in which the conversion space is in theform of a large area, thin sheet in which the ratio of diameter toconversion length is at least five to one.

8.. A device according to claim 7 in which the said large area and shortlength conversion space is bounded by an array of nozzle elements, aplanar array of emitters and a planar array of collectors.

UNITED STA'IES PATENT OFFICE CERTIFICATE O CQRRECTION Patent N0, DatedFebruary Inventor(s) Alvin M. Marks It is certified that error appearsin the above-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 1, line 65, after heart kinetic power" insert "to electric powerColumn 3, line 30, before first oc currence, insert a Column 4, line 57,"suppled" should read -.supp1ied Column 7, line 12, /k should read (k /kline 43, should read Column 8, line 29, "'I" should read l Column 11,line 28, "360mm" should read 360m Column 12, line 28, "relationship"should read eurrent Column 14, line 2, "n" should read Signed and sealedthis 15th day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. Arresting Officer C. MARSHALL DANN Commissioner ofPatents F ORM PC4050 (10-69) uscoMM-oc 603754 69 US GOVERNMENT PRINTINGOFFICE: 869-930

1. In a power conversion device utilizing a charged aerosol as atransducer, an emitter array comprising a plurality of charge emittersto form and charge the charged aerosol, a conversion space to convertthe heat kinetic power of the charged aerosol to electric power, anexciter electrode for the emitters, said emitters per unit areaexceeding the number of exciter electrodes per unit area by a minimumpoint density of at least five points per exciter electrode, and acollector array for discharging the charged aerosol and transmitting theelectric power to an external load.
 2. A device according to claim 1 inwhich the emitter array per exciter electrode exceeds the minimum pointdensity by one or more orders of magnitude and in which the distancebetween the exciter electrode and the emitters is less than 2mm wherebythe potential difference between emitter and exciter electrodes is lessthan 1,000 volts, wherein the minimum point density is n a2 (U/L) wherea2 is the array constant and is of the order of 0.5, U is the velocityof the charged aerosol in meters per second, and L is the length of theconversion space in meters. (whereby ions are emitted to form a chargedaerosol in the conversion space at maximum current density at incipientspark breakdown.)
 3. A device according to claim 2 in which theconversion space length is less than 2 millimeters and in which thearrays exceed 1 point per mm2 employing less than 100 volts potentialdifference between emitter and the exciter electrode, providing outputelectric power at less than 10,000 volts.
 4. A device according to claim1 in which a mixture condensation process is employed to charge and formthe charged aerosol.
 5. A device according to claim 4 in whichsuperheated vapor is emitted from orifices between the point emitters.6. A device according to claim 1 in which the emitter exciter andcollector arrays comprise linear arrays.
 7. A device according to claim1 in which the conversion space is in the form of a large area, thinsheet in which the ratio of diameter to conversion length is at leastfive to one.
 8. A device according to claim 7 in which the said largearea and short length conversion space is bounded by an array of nozzleelements, a planar array of emitters and a planar array of collectors.